Show NEED_BL.TXT if error occurs during BL update
Show NEED_BL.TXT if error occurs during BL update

To make sure the user does not leave their device in a state where the
bootloader is missing, display NEED_BL.TXT on the filesystem until
a good bootloader image is flashed.

sg-/DAPLink,google/DAPLink-port,google/DAPLink-port,google/DAPLink-port,google/DAPLink-port,sg-/DAPLink,sg-/DAPLink